26. Edward Packard's The Cave of Time (Choose Your Own Adventure #1) (1979). How convenient that the first of this series is a time travel adventure, but, really, The Cave of Time is just the token representative of this franchise's insane significance in indoctrinating the youf of many generations into science fictional narratives.

27. Thomas Disch's The Brave Little Toaster (1980). Yes, it is about a toaster. And yes, it became a (amazeballs) movie with songs about trash compactors. But also, yes, it is science fiction that's about our relationship with inanimate objects and the stuffs of life. It is about the balance between progress and nostalgic, the tension between "owner" and "owned", loyalty and slavery and, to no small degree, robots and machine sentience. Also, this song is awesome.

28. Julian May's The Saga of the Exiles (1981 - 1984). Sadly, not every selection can possess the same level of literary significance as The Brave Little Toaster. But The Saga of the Exiles is a sterling example of the Vast SF Epic. In a semi-utopian future, the malcontents and misfits throw themselves through a portal to Earth's distant past. There they find that they have company: two disgruntled species of aliens. The four book series juggles politics, adventure, psychic battles and a quest or two. A great example of SF as entertainment - made more so by the complex plot and well-developed characters.

29. Raymond Briggs' When the Wind Blows (1982). With apologies to Pat Frank's Alas, Babylon, Nevil Shute's On the Beach and Simon Morden's Thy Kingdom Come, I think this slim and poignant graphic novel makes the most essential of the essential post-nuclear reads. In a few short (and beautifully illustrated) pages, Mr. Briggs brings home the real horrors of the apocalypse.

30. Tim Powers' The Anubis Gates (1983). One of the most cleverly-crafted time travel novels and also a sterling representative of steampunk's literary side, in which the values and history of the 19th century is inextricably woven throughout the book.

31. William Gibson Neuromancer (1984). Just as compelling and prescient now as it was in 1984. The technology feels a bit clunky and dated, but tech-based SF does get... clunky and dated. Neuromancer succeeds where many of its cyberpunk peers fail because it isn't reliant on the 'cyber' - the novel focuses on the revolutionary relationship of Case and Molly to the system that created them.

32. Margaret Atwood's The Handmaid's Tale (1985). Yup.

33. Orson Scott Card's Ender's Game (1985). This is a problematic book from an author with deeply problematic views, and, I put it on here despite every possible reason to avoid it. Ender's Game is an amazing book that touches on eugenics, child soldiers, the nuclear family, the dehumanising of the soldier and the intangible, psychological horrors of war. It also has the Battle School fights, which are like the great SF 'sports story' ever told. (I'd argue that even Mr. Card doesn't know how he got Ender's Game right, as evidenced by the endless sequels, prequels and re-quels that have followed.) Buy it used.

34. Haruki Murakami's Hard-Boiled Wonderland and the End of the World (1985). Speaking of psychological horrors, this novel - one of Murakami's best - probes inside the layers and layers and layers of the human mind. A genre-bending, indescribable masterpiece that feels a bit like Slaughterhouse V, a bit like Chandler and mostly something completely unique.

35. Alan Moore's Watchmen (1986). Superheroes are arguably science fictional, but this is also a stunning alternate history and one of the best SF Cold War narratives. Mr. Moore's argument against the filming of his work has always been that he writes stories bespoke to their media - and it is hard to argue against the ultimate superhero narrative existing as anything besides a comic book.

36. Pat Cadigan's Mindplayers (1987). Extremely dense and wonderfully trippy, but the style of Mindplayers matches its substance. In a future where psychosis comes in pill form, this book explores the results and repercussions of a free-wheeling existence where perception is both unreliable and mutable. It is a concept that simply wouldn't work in the hands of a lesser writer, but Ms. Cadigan gets the reader into Ally (the protagonist's) head.

37. Warhammer 40,000 (1987). "In the grim darkness of the far future, there is only war..." If Dungeons & Dragons is inextricably linked to the creation of modern fantasy (and it is), only one science fiction game can boast the same level sort of reach. A quick flick through the basic manual shows why - this is a future unlike any other, a hideous, eternal conflict that pits the hideous against the horrific. As a tabletop game, 40k also brings with it a different philosophy from that of the conventional heroic narrative: there are no absolutes, only factions, each convinced of their own right. Dismiss this as 'toy soldiers' at your own peril, no other book on this list has had as much direct influence on modern science fiction.

38. Iain Banks' The Player of Games (1988). There are, arguably, layers of meaning to Mr. Banks' space operas - cultural perspective and technology and stuff. I'm not wholly convinced. Nor do I need to be - Mr. Banks is one of the great storytellers of the genre, and The Player of Games, the most epic battle of boardgames since Death played chess, is one of the best of its class.

39. Michael Crichton's Jurassic Park (1990). Touchscreen computers, Chaos Theory, gene tampering, evil billionaires and velociraptors. What's not to love? Twenty years later, still the great SF thriller, in the way that it blends together action, heroism, 'plausible' science and mystery.

40. Richard Russo's Destroying Angel (1992). Three cyberpunk novels deemed 'essential' is probably excessive, but, unlike Mindplayers and Neuromancer, Richard Russo's bleak vision of near-future San Francisco also crosses over into noir. There's a mystery and some cyberpseudosciencehandwaviness, but the first Carlucci story is mostly about a battle for souls - bottomed-out players (good and evil) trying to crawl towards their particular light.

41. Nancy Kress' Beggars in Spain (1993). A single speculative twist - a gene that removes the need to sleep - exploded out over the course of a novel. The science is silly (and gets progressively sillier), but Ms. Kress looks into the social consequences of the haves/have-nots (Sleepers and Sleepless) and doesn't hesitate to discuss the ethics of being "chosen".

42. Simon Green's Deathstalker (1995). The largest, most outlandish space opera concievable as a motley group of superhumans find bigger and bigger guns (and fire them). The series goes on endlessly, with the guns getting ever bigger and the plot twists ever sillier. But Deathstalker is one link in a long chain of shamelessly escapist SF that goes back to Burroughs and Brackett and will go forward until the end of time. It is essential because it can't be ignored... and I really enjoy it.

43. Koushun Takami's Battle Royale (1999). Arguably, this position belongs to Suzanne Collins' The Hunger Games (2008), but, in this case, talent (and precedence) supersede scale. Battle Royale is the gut-churning story of a dystopian future in which schoolkids fight to the death. Whereas Collins tries to mitigate the horror by keeping her heroine free of moral ambiguity, Battle Royale is relentless in picturing the depths to which "innocents" can fall. And it is all the more effective for it.

44. China Miéville's Perdido Street Station (2000). Another author I'd like to have on twice. The City & The City is simply astounding, but, in this case, I think the way that Perdido talks specifically about science - its repercussions, ethics, commitments & demands - makes it more relevant to a list of essential science fiction. Plus, like all of Mr. Miéville's works, there's a heady political subtext in here about freedom, revolution and the rights of the individual vs those of the state.

45. Tricia Sullivan's Maul (2003). Two futures - one real, one virtual. Two middle-class teenage girls try to survive them both. A plague has wiped out men, leaving the survivors as objects, not agents. Meanwhile, ambitious women use clones and children as currency, and there's a wild splatterpunk anti-commercial streak that not only links the whole thing together, but makes it surprisingly fun. Described as post-cyberpunk, post-feminist, post-apocalyptic... Maul has posted itself way out there on its own.

46. Sophia McDougall's Romanitas (2005 - 2011). A stunning example of a modern alternate history, as the series doesn't get distracted by the 'big idea' of the setting. (Compared to, say De Camp's time travel novel, Lest Darkness Fall (1955) which is a) racist and b) all ZOMG ROMANZ!) Romanitas and its two sequels written in a way to parallel their years of release in the real (er, our) world. Ms. McDougall doesn't shy from discussing the tricky issues of both times - so the novels touch on terrorism as much as they do slavery. They're also brilliantly character-driven and filled with unexpected, but oh-so-right plot twists. (Another series hotly contesting this particular spot: Jon Courtenay Grimwood's Arabesk).

47. Nick Mamatas' Under My Roof (2007). Judging books from the past five years is tricky, but Under My Roof, a little-known satire by Mr. Mamatas, encapsulates a whole sub-sub-genre of wry, ostensibly young adult satire. Herbert Weinberg's father builds a nuclear bomb and Weinbergia (his house) secedes from the rest of the United States. His actions, as viewed through the eyes of his (telepathic) son, have unintended consequences, and, before long, Herbert is seeing the entire world change.

48. Jonathan Green's Leviathan Rising (2008). If half of steampunk is in the tradition of The Anubis Gates, the other half is well-represented by Mr. Green's long-running Pax Britannia series. It is pure, wonderful pulp thinly veiled behind the Victorian aesthetic. In this volume, special agent Ulysses Quicksilver battles the agents of a foreign power while on a massive steam-powered submarine. (Also included: mechanical squid.) Unlike, say, Cherie Priest of Gail Carriger, Mr. Green's work remains firmly ensconced in science fiction and, although certainly fantastic, never edges across into fantasy.

49. Lauren Beukes' Zoo City (2010). I'm not sure there's a safer pick as a contemporary SF "essential". Zoo City has all the makings of a future classic - using science fictional elements to prompt a discussion about apartheid and post-apartheid South Africa, class division, pop culture and even media savagery.

50. Lavie Tidhar's Osama (2011). More science fiction noir, beautifully written and astoundingly powerful. Osama doesn't try to make sense of a world that is, in many ways, senseless. But by incorporating science fictional elements, Mr. Tidhar's book gains the distance to talk about terrorism and 9/11 in a way that conventional literary fiction cannot.

...and that's fifty. What surprised you? What'd I miss? What shocking oversight should I be reading right now?

26. Edward Packard's The Cave of Time (Choose Your Own Adventure #1) (1979). How convenient that the first of this series is a time travel adventure, but, really, The Cave of Time is just the token representative of this franchise's insane significance in indoctrinating the youf of many generations into science fictional narratives.

27. Thomas Disch's The Brave Little Toaster (1980). Yes, it is about a toaster. And yes, it became a (amazeballs) movie with songs about trash compactors. But also, yes, it is science fiction that's about our relationship with inanimate objects and the stuffs of life. It is about the balance between progress and nostalgic, the tension between "owner" and "owned", loyalty and slavery and, to no small degree, robots and machine sentience. Also, this song is awesome.

28. Julian May's The Saga of the Exiles (1981 - 1984). Sadly, not every selection can possess the same level of literary significance as The Brave Little Toaster. But The Saga of the Exiles is a sterling example of the Vast SF Epic. In a semi-utopian future, the malcontents and misfits throw themselves through a portal to Earth's distant past. There they find that they have company: two disgruntled species of aliens. The four book series juggles politics, adventure, psychic battles and a quest or two. A great example of SF as entertainment - made more so by the complex plot and well-developed characters.

29. Raymond Briggs' When the Wind Blows (1982). With apologies to Pat Frank's Alas, Babylon, Nevil Shute's On the Beach and Simon Morden's Thy Kingdom Come, I think this slim and poignant graphic novel makes the most essential of the essential post-nuclear reads. In a few short (and beautifully illustrated) pages, Mr. Briggs brings home the real horrors of the apocalypse.